G. E. Mitchell

Influence of Rumen Fermentation on Response to Endophyte—Infected Tall Fescue Seed Measured by a Rat Bioassay

Possible alteration of toxicity of endophyte-infected tall fescue by ruminal fermentation was studied using 28 Harlan Sprague-Dawley rats (avg. initial wt., 141 g). These were assigned randomly to one of four treatments in a 2*2 factorial consisting of a 14-day growth period with weights and feed consumption data determined on days 0, 5, 10 and 14. Treatments were: endophyte-infected Kentucky-31 tall fescue seed (E+) or endophyte free Johnstone tall fescue seed (E-) that was incubated for 0 (NON) or 24 hours (INC) with rumen fluid collected from a 290-kg cannulated steer fed a diet containing 37% endophyte-infected tall fescue hay. Diets consisted of 50% lab chow, 39% fescue seed and 11% rumen contents (air-dry basis). Alkaloid content (N-acetyl plus N-formyl loline) for the four diets were 2540, 2680, 0, and 0 micrograms/g for E+NON, E+INC, E-NON, and E-INC diets, respectively. E- treatments gained faster, consumed more feed and converted feed more efficiently (P < .05) than did E+ fed groups. No difference in feed intake was observed within E+ treatments, however, the E+INC diet gained faster (P < .05) and converted feed more efficiently (P < .05) than did E+NON fed rats (2.56 vs 1.96 g/d and 5.94 vs 7.51 g of feed/g of gain for gain and feed conversion, respectively). Including endophyte-infected seed in rat diets depressed performance (ie. intake, gain and feed efficiency). This depression was partially alleviated by a 24-hour incubation with rumen fluid contents suggesting that toxicity of endophyte-infected tall fescue is lessened due to rumen microbial action.

High-performance liquid chromatographic determination of 4-methylimidazole in sheep plasma and in ammoniated tall fescue hay.

A method for 4-methylimidazole (4MI) extraction and quantitation in body fluids and forage samples was developed. The procedures involve ion-pair extraction of the compound with the quantitation done by ion-pair liquid chromatography. The results indicate that this high-performance liquid chromatographic method is sensitive, reproducible and more rapid than others that have been previously used. The mean recovery of 4MI from plasma and tall fescue (Festuca arundinacea) hay samples were above 95 and 85%, respectively. The versatility of the procedure makes it suitable for the determination of 4MI in body fluids and in forage samples.

Post-ruminal digestion of starch in the presence of phenolic monomers

Abstract The capacity for phenolic monomers to influence starch digestion was examined in six lambs (21.0 kg) fitted with abomasal and ileal cannulae and fed 455 g dry matter per day of a mixture of alfalfa meal (60%), cottonseed hulls (20%) and tall fescue hay (19%). An average of 68.3 g starch per day was infused continuously into the abomasum and ferulic and p-coumaric acids were administered orally in gelatin capsules. Dietary influences were determined in a replicated Latin square crossover design using both Cr2O3: nutrient and lignin: nutrient ratios to calculate digestibility values. Pre-ileal starch digestion coefficients were 97.9, 97.9 and 97.8% for control, ferulic acid and p-coumaric acid treatments, respectively, by Cr2O3: nutrient ratio, and 98.5, 98.5 and 98.5% by lignin: nutrient ratio. Total tract strach digestion coefficients were 99.4, 99.5 and 99.4% for control, ferulic acid and p-coumaric acid treatments, respectively, by Cr2O3: nutrient ratio, and 99.5, 99.7 and 99.5% by the lignin: nutrient ratio method. No significant effects of phenolic compounds upon post-ruminal digestion of starch, neutral detergent fiber or acid detergent fiber were observed.

Ammoniation to Reduce the Toxicity of Endophyte-Infected Tall Fescue Seed fed to Rats

To assess the efficacy of ammoniation in the detoxification of endophyte-infected tall fescue (Festuca arundinacea Schreb), 40 male Harlan Sprague-Dawley rats were randomly assigned to the following four treatments for 28 d: endophyte-free (E-), endophyte-infected (E+), ammoniated (2% dry matter basis, 7 d) endophyte-free (AE-), and ammoniated endophyte-infected (AE+) tall fescue seed. Total pyrrolizidine alkaloid (N-acetyl and N-formyl loline) and ergovaline contents of endophyte-infected fescue seed were reduced 24 and 54%, respectively, by ammoniation. Endophyte-infected treatment groups had lower (P < 0.01) daily feed intakes (DFI), daily weight gains (DWG), feed efficiencies, and primary serum hemagglutination titers to sheep red blood cell (SRBC) immunization than endophyte-free treatment groups. Performance parameters were higher (P < 0.01) for ammoniated diets in comparison to non-ammoniated diets; however, anti-SRBC titers were not significantly different. When compared to the E+ diet, the AE+ diet increased (P < 0.01) DFI (24%), DWG (41%) and feed efficiency (13%).

Essential fatty acid status of colostrum-deprived gnotobiotic and conventional lambs: Organ fatty acid composition

Abstract Gnotobiotic (GN) and conventional (CV) colostrum-deprived lambs were fed diets deficient (D) or supplemented with. 32% of the total calories as linoleic acid (L). Plasma and organ fatty acid compositions were assessed after 2 mo. of the dietary and environmental regimens. Linoleic acid deficiency in GN and CV lambs generally resulted in decreases of linoleic acid in plasma, liver and kidney samples and increases in oleic and eicosatrienoic acids. The triene/tetraene ratios (20:3n9/20:4n6) for plasma, kidney and liver increased in the D vs L groups. However, the elevated triene/tetraene ratios observed for the L groups (